1. Field of the Invention
This invention concerns an electromagnetically actuated ball-type injector, intended for the injection of fluid, expecially fuel in internal combustion engines.
2. Description of the Prior Art
An injector of this type has been previously described in an earlier French Pat. No. 2166734 and its supplement No. 2211049 filed by the present application.
They describe in particular an electromagnetically actuated injector comprising a casing within which is located a core including a fluid inlet passage, an actuating coil surrounding the core, a chamber between the cover and the core and which contains a ball to close the injection passage formed in the cover, said ball being attracted in the direction which opens the injection passage by the magnetic field created by the actuating coil against an elastic system which urges the ball back against its seat.
In this embodiment, the end of the core must be machined so as to locate in it, first, the elastic system which may be a simple coil spring, and second, a fitted part made of a nonmagnetic material to keep the ball from adhering to the core because of residual magnetism. This machining does not pose any particular problems, but substantially increases the manufacturing costs of the injector.
Moreover, despite the return force of the spring, tightness of the ball on its seat is not always achieved with a satisfactory degree of efficiency.
Finally, it may happen that turbulence associated with cavitation phenomena occurs, as is customary beneath the seat of the injector when the fluid reaches a temperature at which is begins to vaporize. The flow in the injection conduit is then altered as a function of temperature.